LAUSR

BACKGROUND Cancer rates in rural areas across the United States have different patterns than in urban areas. This study examines associations between rurality and incidence for the top five cancers in California and evaluates whether these associations vary jointly by sex, race, and ethnicity. METHODS We use 2015-2019 California Cancer Registry data to compare incidence rate ratios (IRRs) and trends for breast, prostate, lung, colorectal, and skin (melanoma) cancers. We leverage census tract aggregation zones and seven levels of % rural population (0%, >0-<10%, 10-<20%, 20-<30%, 30-<40%, 40-<50%, and 50+%). RESULTS Zones with higher proportions of rural population were significantly associated with lower incidence of female breast cancer and prostate cancer, though the trends were not significant overall. Zones with higher proportions of rural population were significantly associated with higher incidence of lung cancer and melanoma. There were no statistically significant trends for colorectal cancer overall. Comparing areas with ≥50% rural population with areas with 0% rural population, the IRR for lung cancer in Hispanic females was higher (IRR = 1.43, 95% CI (1.17, 1.74)) than in Hispanic males (IRR = 0.90, 95% CI (0.72, 1.11)). Also in areas with ≥50% rural population, the IRR for melanoma was higher in Hispanic females (IRR = 1.75, 95% CI (1.23, 2.45)) than non-Hispanic White females (IRR = 0.87 95% CI (0.80, 0.95)). CONCLUSION Our findings show that rurality is associated with cancer incidence and underscore the importance of examining rural disparities jointly with sex, race and ethnicity by cancer site.